The larvae of the fly Phytomyza autumnalis mine the leaves of various thistles in the family Cirsium and also some knapweeds (Centaurea family) creating a full depth, greenish, usually linear, mine which is usually upper surface and doubles back on itself. The pupa is metallic black and the anterior spiracles protrude through the lower epidermis. The mines of Phytomyza spinaciae are identical to those of Phytomyza autumnalis and can only be separated by larval and puparium features. The puparium of Phytomyza spinaciae is white whereas Phytomyza autumnalis is black.
Adult: Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.
Leafmine: Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed. In this case the larva or pupa must be photographed.
Wherever the larval foodplants occur.
Mine: October and November
Status in Britain is difficult to determine due to lack of records.
Status in Leicestershire and Rutland not known.
Leicestershire & Rutland Map
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Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015